Anal Cancer Screening: What Gay and Bi Men Should Know

Anal cancer is rare in the general population. But gay and bisexual men face a much higher risk. New research now shows that screening can prevent most cases. The findings are changing how doctors approach this disease.

The ANCHOR study, published in the New England Journal of Medicine in 2022, found that treating precancerous lesions cuts anal cancer risk by 57 percent. The study followed more than 4,400 people living with HIV. It is the first large trial to prove that screening works.

Why Gay and Bi Men Are at Higher Risk

Anal cancer is almost always caused by HPV, the human papillomavirus. HPV spreads through skin contact during sex. Most sexually active adults get it at some point. In most people, the body clears the virus on its own.

But some HPV types can cause cell changes that lead to cancer. Receptive anal sex raises the risk of HPV infection in that area. Men who have sex with men therefore face higher rates of anal HPV than the general population.

The numbers are clear. According to the US Centers for Disease Control and Prevention, gay and bisexual men are about 20 times more likely to get anal cancer than heterosexual men. For men living with HIV, the risk is even higher. Studies estimate the rate is around 85 per 100,000 per year in HIV-positive gay men. That is similar to cervical cancer rates before screening became standard.

What the ANCHOR Study Changed

For years, doctors debated whether screening for anal precancer actually helped. Cervical cancer screening has saved millions of lives. But there was no proof that the same approach worked for the anus.

ANCHOR ended that debate. Researchers randomly assigned participants to either treatment of precancerous lesions or active monitoring. The treatment group had far fewer cancer cases. The trial was stopped early because the benefit was so clear.

Based on these results, US guidelines now recommend anal cancer screening for people living with HIV who are 35 or older if they are gay or bisexual men, and 45 or older for others. The International Anal Neoplasia Society also issued screening guidance in 2024.

How Screening Works

Screening for anal cancer follows a similar logic to cervical screening. There are two main steps.

The first step is an anal Pap test. A clinician uses a small swab to collect cells from inside the anus. The sample goes to a lab. If abnormal cells are found, the next step is high-resolution anoscopy, or HRA. This uses a small scope and a magnifying lens to look closely at the tissue.

If precancerous lesions are spotted during HRA, they can be treated. Common methods include freezing, burning with electric current, or topical creams. Treatment is done in a clinic and usually takes minutes.

Access to HRA remains a problem. Trained specialists are scarce, even in major cities. The Dutch HIV Association and clinics linked to HIV care networks are working to expand training.

The Role of the HPV Vaccine

Prevention is better than treatment. The HPV vaccine, marketed as Gardasil 9, protects against the nine HPV types that cause most cancers. It works best when given before someone becomes sexually active.

The Dutch RIVM added boys to the national HPV vaccination programme in 2022. Boys and girls are now offered the vaccine at age 10. Catch-up vaccination is available for young adults up to 26 in many countries.

Gay and bisexual men who missed the vaccine as teenagers can still benefit. Studies show the vaccine reduces new HPV infections even in adults who are already sexually active. The WHO recommends vaccination for men who have sex with men up to age 26, and sometimes older depending on national policy.

Symptoms to Watch For

Most anal precancers cause no symptoms. That is why screening matters. But early-stage cancer can sometimes cause warning signs.

• Bleeding from the anus that is not clearly from haemorrhoids
• A lump or mass that does not go away
• Persistent itching or pain
• Changes in bowel habits that last more than a few weeks
• Discharge or unusual mucus

These symptoms have many possible causes. Most are not cancer. But they should be checked by a doctor, especially in people at higher risk.

What to Ask Your Doctor

Awareness among general practitioners varies. Some are well informed about anal cancer risk in gay and bisexual men. Others are not. It can help to come prepared.

Useful questions include whether you should have an anal Pap test, whether HRA is available in your region, and whether you are eligible for catch-up HPV vaccination. If you live with HIV, your HIV specialist is often the best starting point. Many HIV clinics now offer screening as part of routine care.

Cost and coverage differ by country. In the Netherlands, screening is generally covered for people living with HIV. In the UK, NHS provision is limited but growing. In the US, Medicare began covering screening for high-risk groups in 2024.

The Bigger Picture

Anal cancer remains uncommon overall. But for gay and bisexual men, especially those living with HIV, the risk is real and rising. The good news is that the disease is largely preventable.

Vaccination prevents most HPV infections. Screening catches precancerous changes before they turn into cancer. Treatment of those changes works. The pieces of a prevention strategy are now in place. The challenge is making sure they reach the people who need them.

If you are a gay or bisexual man over 35, or living with HIV, talk to your doctor. Ask about your risk. Ask about screening. And if you missed the HPV vaccine, ask whether catch-up vaccination still makes sense for you.